Regular margarine contains of 80% fat by weight and 20% aqueous phase (with a maximum water content of 16%). Regular margarine is a water-in-oil emulsion in which the water phase is emulsified in oil phase by protein (usually milk protein as an emulsifier). The oil phase in most margarines contain 17-20% saturated fat, however between 30-35% of saturated fat is trans fat which is produced during the manufacturing of partially hydrogenation of fat. The amount of trans fat can be varied in regular margarine (30-50%) depending upon the quality of fat. In a normal processing of margarine (a water-in-oil emulsion) the fat phase is thermally prepared by dissolving the fat in liquid oil and mixing with aqueous phase (containing water, emulsifier, salt, preservative and color) to produce a water-in-oil emulsion. This emulsion is rapidly cooled in a scraped surface heat exchanger (so called Votator or Perfector) to achieve fat crystal nucleation. The Votator consists of two main parts (A and B units). The “A” unit is a coolant and supercools the margarine below its crystallization point to produce fat crystals; whereas the “B” unit is a pin worker in which the mass is worked vigorously to complete crystal formation and reduce the crystal size and then allowed to rest to achieve phase stabilization prior to packaging.
For many years, it has been known that the saturated and trans fats are “unhealthy” in margarine. Most margarines on the market today, however, are manufactured with partially hydrogenated fats and as a consequence can still contain substantial quantities of trans and saturated fatty acids. Data from the Institute of Shortening and Edible Oils (ISEO) indicate that high levels of trans fats in the diet may raise LDL (bad) cholesterol levels and lower HDL (good) cholesterol levels. The concern about saturated fatty acids was initially addressed when the industry launched soft tub margarines. For tub-type margarines, a typical composition of the fat phase is 33-52% monounsaturated fat, 29-48% polyunsaturated fat and 17-20% saturated fat. Tub margarine with 17-20% saturated fat is stable against coalescence of water droplets since water droplets become trapped within the saturated fat crystal network. If regular margarine (water-in-oil emulsion) prepared with low saturated fat (5-10%), the stability and mouthful of finished margarine would be reduced and water droplets become coalesced and eventually the oil and water phase will be separated. It is almost impossible to produce and stabilize a regular margarine with 2-4% added solid fat using traditional regular margarine manufacturing procedure.
Although recent introduction of margarines with intersterified fat to the market eliminated the trans fats, it did not reduce the amount of saturated fats significantly. Interesterification is a process that rearranges the fatty acid groups within and between different triglycerides to adjust the melting range of a fat and oil mixture. As a consequence the solid fat content (SFC) of the mixture reduces due to dissolved intermediate melting point triglycerides in the oil and show less SFC, but in fact the saturated fatty acids remain high. A typical margarine produced with intersterified fat contain 10-15% saturates. The process of random interesterification of fat is expensive, using toxic chemicals and adding significant costs to the manufacture of products contain intersterified fats.
A recent invention in production of margarine involving a double emulsion system eliminates trans fats and reduces the added solid fat down to 4%, however this procedure requires production and stabilization of two oil-in-water emulsions and mixing them under certain conditions to avoid phase separation prior to solidification and stabilization in the form of oil-in-water-in-oil emulsion system (see Kakuda et al. PCT Patent Application WO 01/80659, published on Nov. 1, 2001). This procedure also requires additional machineries such as homogenizer and preparation of emulsions in a batch system and it takes a long time to finish the product, which affects the product cost. In this procedure the uniformity of the product's texture is less consistent and can be vary in each batch.
There remains a need for a simple and economical process to produce a regular margarine (water-in-oil emulsion) with no trans fatty acids and minimal (for e.g. 2-4%) amounts of saturated fats. Such a procedure should not require additional equipment and be amenable to use in any regular margarine production line.